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Pythium vexans causing patch canker of rubber trees on Hainan Island, China.

This is the first report of patch canker disease of rubber trees (clone RRIM600) in China. It is characterized by discrete irregular patches of rotted, discolored bark and wood, accompanied by a decrease in latex flow. A total of seven isolates of Pythium vexans were obtained from the diseased bark of the trunks and roots of rubber trees. Inoculating these isolates into healthy, mature rubber trees resulted in symptoms similar to patch canker and the same fungal species was re-isolated from the diseased tissues. This is also the first record of Py. vexans in Hainan.

Base Sequence↗

Removal of solid silicone rubber exoplants after retinal detachment surgery.

A prospective study of 255 eyes undergoing scleral buckling procedures with solid silicone rubber elements as exoplants disclosed a 1.2% incidence (three of 255 eyes) of buckling element removal after a minimum follow-up period of two years. This rate was lower than that reported in series using solid silicone rubber implants or sponge silicone rubber exoplants.

Bacterial Infections↗

Rubber dam isolation in a difficult situation.

Rubber dam retainers can be modified easily in the dental office to enable the dentist to isolate teeth with difficult restorative problems with the rubber dam. Isolation with the rubber dam enhances visibility and access and gives the dentist the opportunity to render safe, restorative care of high quality to the patient.

Dental Caries↗

Prevention of acquired immunodeficiency syndrome and hepatitis B. Part III: Disinfection of hydrophilic silicone rubber impression materials.

The effect of glutaraldehyde solution, an effective disinfectant for viruses, on the dimensional stability of hydrophilic silicone rubber impression materials was evaluated in this study. Disinfection with 2% glutaraldehyde solution showed a slight expanding effect on the dimensional stability of the hydrophilic silicone rubber impression materials (less than 0.03%). It was revealed that glutaraldehyde can be used for the disinfection of hydrophilic silicone rubber impression materials. Attention should be paid, however, to the conditions for investment or casting to eliminate the expanding effect of this disinfecting procedure.

Acquired Immunodeficiency Syndrome↗

Comparative biotolerance of polyacrylamide-agarose gel, silicone rubber and microporous PTFE as soft tissue implants.

A comparative study has been carried out on the biotolerance to subcutaneous, intramuscular and intraperitoneal implants of silicone rubber, microporous PTFE and polyacrylamide-agarose gel for 6 wk in the rat. Assessment was quantitative histology for capsule thickness, fibroblast density, mononuclear cell density, multinucleated giant cell density and also collagen packing density. The trial polymers were compared to historical data on healing in dummy procedures and on two hydrophilic graft copolymers of high biotolerance namely polyethylene-acrylic acid and microporous polypropylene-acrylic acid. The rank ordering of the trial polymers for all criteria except collagen packing, was for the least response to be to polyacrylamide-agarose and the most to silicone rubber, with the differences being significant (p less than 0.05) for capsule thickness and mononuclear cell density. Polyacrylamide-agarose was similar in response to the two hydrophilic copolymers; microporous PTFE was slightly more reactive and silicone rubber was significantly more reactive (p less than 0.05).

Acrylic Resins↗

In vivo degradation of polymers. II. Change of mechanical properties and cross-link density in silicone rubber pacemaker lead insulations during long-term implantation in the human body.

The results of mechanical testing, microscopic examinations and swelling of the explanted clinically used silicone rubber pacemaker lead insulations are presented. An experimental set of 100 lead insulations implanted for times ranging from 3 d to 11 yr were evaluated for change of mechanical properties and cross-link density during clinical use. The results show that the silicone rubber tubing suffers a gradual structural change due to its exposure to the physiological environment of the human body. A spiral deformation pattern due to the permanent set of the silicone rubber tubing in contact with the electrode leading wire was observed.

Equipment Failure↗

ppHEMA-modified silicone rubber film towards improving rabbit corneal epithelial cell attachment and growth.

A plasma polymerized HEMA (ppHEMA) film was prepared by plasma deposition polymerization onto an elastic material, silicone rubber. The surfaces of control, argon plasma-treated, and ppHEMA-modified silicone rubber were characterized by ESCA, FTIR-ATR and SEM techniques. ESCA verified the respective chemical shift of control and ppHEMA-modified films. The presence of the ppHEMA was also verified by ESCA. The introduction of ppHEMA onto a hydrophobic support provided an adequate surface for rabbit corneal epithelial cell attachment and growth. Cell attachment and growth onto these surfaces were examined by light microscopy. Cell attachment onto the control and the argon plasma-treated surface was negligible, while improved attachment and growth of rabbit corneal epithelium cells was demonstrated on the ppHEMA-modified polymeric surface. The ppHEMA-modified silicone rubber surface demonstrated a confluent cell layer after 72 h.

Animals↗

Cardiovascular cavities cast in silicone rubber as an adjunct to post-mortem examination of the heart.

We used silicone rubber as a material for making post-mortem casts of cavities in 21 human hearts, 16 of them congenitally malformed, 13 after surgical reconstruction (Fontan and Norwood procedures) and 4 after reconstruction had been performed posts mortem for study purposes. The organs were either fresh, or had been perfusion fixed with formalin prior to casting. When suitable silicone rubber and catalyst were used, we found that casts allowed a very clear view of chamber morphology, and, where surgery had been performed, of any vascular constriction or distortion. We made casts of the aortic sinus and coronary arteries in 3 adult hearts, demonstrating the location and extent of indentation due to atheromatous deposits. The resilience and non-adhesiveness of the silicone rubber allowed casts to be extracted without recourse to corrosion. The surrounding tissues, with the exception of trapped trabeculations and valve structures, were then available for conventional pathological examination. We propose that the relatively simple technique has important applications, not practicable using earlier casting materials, for the study of cardiovascular morphology, and for post-mortem evaluation of stenosed or surgically reconstructed vessels.

Adult↗

Fine bore silicone rubber and polyurethane catheters for the delivery of complete intravenous nutrition via a peripheral vein.

The aim of the study was to evaluate two fine bore catheters for the delivery of complete intravenous nutrition (IVN), of osmolality 1250 mosm/kg, via a peripheral vein. 50 patients were randomised to receive either a 23G silicone rubber catheter or 22G polyurethane catheter. The median duration of feeding was 9 days for silicone rubber catheters and 10 days for polyurethane catheters. Silicone rubber catheters developed complications significantly more frequently (44%) than polyurethane catheters (22%, p < 0.05). There was no significant difference in the median life span of the catheters removed because of complications, nor in the daily risk of thrombophlebitis. 92% of patients who were fed through a polyurethane catheter required only a single catheter for the duration of IVN. The peripheral venous route should be the first choice when the administration of IVN is considered for a period of less than 2 weeks.

Journal Article↗

Black rubber or clear plastic delivery tubing for nitrous oxide: patient preference.

Entonox (a 50:50 mixture of nitrous oxide in oxygen) is given via black rubber corrugated tubing in most obstetric units even though this has been superseded by clear plastic tubing in many operating theatres. This trial has shown that more women in labour preferred using plastic rather than black rubber tubing because it was lighter in weight and devoid of the unpleasant smell associated with the latter. Women also suffered a greater degree of dizziness while using the black rubber tubing. Clear plastic tubing seems a sensible alternative for the delivery of Entonox now that the risks associated with the build up of static charge have little importance. It is cheap, odourless and lightweight, it can be cut to any length, fits standard 22 mm connections, is easy to clean and although durable is potentially disposable.

Journal Article↗

Capsule endoscopy for the diagnosis and follow-up of blue rubber bleb nevus syndrome.

Blue rubber bleb nevus syndrome is a rare disorder characterised by cutaneous and gastrointestinal vascular malformations. A 31-year-old man came under our observation with obscure gastrointestinal bleeding. Hemangiomas on his back and the multiple bluish vascular lesions in the distal ileum revealed by capsule endoscopy led to the diagnosis of blue rubber bleb nevus syndrome. The patient was treated with octreotide to prevent rebleeding. During the 12 months of treatment he had no gastrointestinal bleeding episodes or anaemia. Then repeat capsule endoscopy showed that the small bowel vascular lesions were unchanged. Capsule endoscopy may be a useful tool for diagnosing and monitoring the effects of therapy in patients with blue rubber bleb nevus syndrome.

Adult↗

Blunt and penetrating injuries caused by rubber bullets during the Israeli-Arab conflict in October, 2000: a retrospective study.

BACKGROUND: Low-velocity rubber bullets were used by Israeli police to control riots by Israeli-Arabs in early October, 2000. We aimed to establish the factors that contribute to severity of blunt and penetrating injuries caused by these missiles. METHODS: We analysed medical records of 595 casualties admitted. We assessed relation of severity of injury to type of bullet, anatomical region of injury, and final outcome. Severity of injury was established by the abbreviated injury scale, and we calculated injury severity score. FINDINGS: 151 males and one female (age range 11-59 years) were included in the study, in whom 201 proven injuries by rubber bullets were detected. Injuries were distributed randomly over the body surface and were mostly located in the limbs (n=73), but those to the head, neck, and face (61), chest (39), back (16), and abdomen (12) were also frequently noted. 93 (61%) patients had blunt injuries and 59 (39%) penetrating ones. Severity of injury was dependent on ballistic features of the bullet, firing range, and anatomic site of impact. Two casualties died after a penetrating ocular injury into the brain and one died as a result of postoperative aspiration after a knee injury. INTERPRETATION: Resistance of the body surface at the site of impact (elastic limit) is the important factor that ascertains whether a blunt or penetrating injury is inflicted and its severity. Inaccuracy of rubber bullets and improper aiming and range of use resulted in severe injury and death in a substantial number of people. This ammunition should therefore not be considered a safe method of crowd control.

Adolescent↗

Silicone rubber-hydrogel composites as polymeric biomaterials. IX. Composites containing powdery polyacrylamide hydrogel.

A composite material has been prepared consisting of a silicone rubber matrix and particulate lightly cross-linked polyacrylamide hydrogel. The material, resembling common silicone rubber, is hydrophilic and swells in water like hydrogels. The polyacrylamide has a high specific surface area, a relatively low content of water-soluble low-molecular-weight compounds and, owing to its non-ionogenic character, a pH-independent swelling degree. For the composite material consisting of the silicone rubber and very fine powdery cross-linked polyacrylamide, we have measured the rate of swelling in water, the mechanical properties (tensile strength, break elongation, hardness, resilience), biological properties (implantation test, cytotoxicity, cell cultivation) and UV absorption of its water extracts. The polyacrylamide and polysiloxane purity, as the composite material starting components, has been determined to be satisfactory. As a result, a high swelling rate of the prepared composite material has been observed, resulting in reaching more than 70% wt of water of the equilibrium swelling. The results show that the composite material is suitable for biological and medical use.

3T3 Cells↗

Orbital lesions in the blue rubber bleb nevus syndrome.

PURPOSE: To identify ophthalmologic manifestations of the blue rubber bleb nevus syndrome, a rare cutaneovisceral hemangiomatosis. METHODS: The authors report two patients with a diagnosis of blue rubber bleb nevus syndrome with orbital hemangiomas. RESULTS: In one patient, the orbital lesion presented with signs and symptoms similar to an orbital varix and in the other with lid ecchymosis from an eyelid lesion. CONCLUSION: Patients with the blue rubber bleb nevus syndrome may have vascular orbital lesions associated with intermittent proptosis. Ophthalmologists should be familiar with the syndrome and its life-threatening complication of gastrointestinal hemorrhage.

Adult↗

Analysis of the properties of silicone rubber maxillofacial prosthetic materials.

OBJECTIVES: Maxillofacial prosthetic materials are used to replace facial parts lost through disease or trauma. Silicone rubbers are the materials of choice, however it is widely accepted that these materials do not possess ideal properties. The objective of this study was to assess the properties of a range of commercially available silicone rubber maxillofacial materials and make recommendations for improvements. METHODS: Specimens of five commonly used maxillofacial materials were prepared in dental flasks according manufacturers instructions. Tear strength, tensile strength, percentage elongation, hardness, water absorption and water contact angles were determined for each material. RESULTS: The tear strength of Factor II, Cosmesil HC and Nusil were all comparable and significantly higher than Cosmesil St and Prestige (p<0.001). Nusil had a significantly higher tensile strength and elongation in comparison to the other materials (p<0.001) and Cosmesil St and Cosmesil HC were significantly harder (p<0.001). Factor II was significantly less wetted and Prestige and Cosmsesil St had a significantly higher water absorption in comparison to the other materials. CONCLUSIONS: None of the commercially available silicone rubber materials possessed ideal properties for use as a maxillofacial prosthetic material. Factor II, however, showed more favourable properties due to it's high tear strength, softness and ease of manipulation.

Absorption↗

Failure of silicone rubber wrist arthroplasty in rheumatoid arthritis.

Of 71 silicone rubber wrist arthroplasties performed between 1976 and 1983, 20% were found to have fractured, and an additional 5% required revision for deformity and pain. In most cases, no specific cause for the failure could be identified. However, excessive wrist motion, overuse, and inadequate surgical technique appear to be contributory. Prosthetic fracture is associated with increasing wrist pain, instability, and deformity with decreasing strength and function. Twelve of 14 fractured prostheses required revision. Eleven of these were revised with another silicone rubber implant, and two of these have refractured. Based on this review, we have narrowed our indications for silicone rubber wrist arthroplasty and now give greater consideration to alternative methods of treatment.

Arthritis, Rheumatoid↗

Mechanical and biological comparison of latex and silicone rubber bands.

Latex rubber bands are routinely used to supply orthodontic force. However, because the incidence of allergic reactions to latex is rising, the use of nonlatex alternatives is increasing, and assessing the mechanical properties of the replacement products is becoming more important. The purposes of this study were to compare the mechanical properties of latex and silicone orthodontic rubber bands through static testing under dry and wet conditions, and to compare their biologic (cytotoxic) properties. Three brands of latex and 1 brand of silicone rubber bands were tested. When extended to 300% of the lumen diameter, the silicone group had an initial force equal to 83% of the product specifications; this was the lowest of the 4 groups. All 4 brands showed notable amounts of force degradation at the 300% extension when subjected to saliva immersion; this approximated a 30% force decay over 2 days. The latex bands all followed a similar pattern of force degradation, whereas the silicone bands showed a greater increase in force decay as the extension length increased. The silicone bands were less cytotoxic than 2 of the 3 types of latex. Although the silicone bands showed the least discrepancy of force degradation between air and saliva conditions, the amount of the force decay was the greatest. Therefore, great improvements in the physical properties of the silicone band are required before they can be considered an acceptable replacement for latex.

Analysis of Variance↗

Comparison of methods for the reduction of acute pain produced by rubber ring castration or tail docking of week-old lambs.

Behavioural and plasma cortisol changes were recorded for groups of eight Suffolk x Greyface lambs subjected to castration or tail docking using rubber rings with and without local anaesthetic treatment. Immediately after application of the rubber ring, local anaesthetic (2 x 0.2 ml 2% lignocaine) was administered either by needle and syringe or by high-pressure needleless injection into each side of the neck of the scrotum or tail at the site of the ring, or by high pressure needleless injection into the testes before ring application. In other groups, the innervation to the scrotum or tail was disabled by crushing with a powered bloodless castrator just proximal to the ring. Measurements were recorded in groups of control (handled) lambs, with and without local anaesthetic treatment. Application of local anaesthetic by high pressure needleless injection had little effect on either plasma cortisol values or behaviour of control lambs. For castration, application of the bloodless castrator and/or local anaesthetic at the ring site reduced the peak plasma cortisol concentration by 50% (P < or = 0.01), the incidence of active behavioural responses by 80 and 64% (P < or = 0.01) respectively, and the time spent in abnormal postures by 68 and 59% (P < or = 0.01) respectively. Both methods were effective in reducing pain for tail docking [active behavioural responses reduced by more than 80% (P < or = 0.01) and abnormal postures by 56% (P < or = 0.01)], although local anaesthetic was more effective, reducing the peak cortisol by 60% (P < or = 0.01) [crushing by 44% (P > 0.05)]. Injection of local anaesthetic into the testes was less effective than injection into the neck of the scrotum at the site of the ring [reduction in abnormal lying postures (P < or = 0.05), 45 vs 71%, respectively]. The rapid action, effectiveness, and ease of application of these experimental methods may provide the basis for commercially viable methods for reducing the acute pain produced by rubber ring castration and tail docking of lambs.

Anesthetics, Local↗